Your First Program

Enemy 1 of 5

Every Dart program starts in main

Unlike scripting languages that run top to bottom the instant you open the file, Dart requires a specific entry point: a function called main. When you run a Dart program, the very first thing that executes is the code inside main() — everything the program does flows from there, directly or indirectly. This is similar to how languages like Java, C, and C++ work, and different from PHP or Python, where code at the top level of a file just runs in order without needing a named entry function.

void main() { ... } breaks down into three parts: void tells Dart this function doesn't hand back a value when it finishes (as opposed to a function that computes and returns something), main is the required name Dart looks for, and the curly braces { } contain the block of code that runs when the program starts.

print() is Dart's basic tool for writing a line of text to the output. It takes one argument — the value to display — automatically converts it to text if it isn't already a string, and adds a newline after it, so consecutive print() calls each land on their own line.

Every statement inside the braces ends with a semicolon (;), matching the C-family style Dart borrows its syntax from. A missing semicolon is one of the most common first errors — Dart's error message will often point near where it expected one, which is a good habit to check first when something doesn't compile.